Their stay begins tomorrow (Thursday) when the Soyuz docks with the station's Zvezda service module at 22:25 GMT. They'll be welcomed aboard by fellow Expedition 24 crew members commander Alexander Skvortsov, and flight engineers Tracy Caldwell Dyson and Mikhail Kornienko.

Walker, 45, is a space rookie. The graduate of Rice University is apparently "the first native Houstonian to be named an astronaut".

Wheelock, 50, a US Army colonel, is on his second trip to the ISS. He previously visited aboard space shuttle Discovery in 2007 on its STS-120 mission.

Yurchikhin, 51, is an ISS vet. This is his third trip into space and his second long-duration stay aboard the station. In October 2002, he was aboard space shuttle Atlantis on its STS-112 mission to the station, and he also spent six months aloft as 2007 Expedition 15 commander.

Walker, Wheelock and Yurchikhin will in September become the Expedition 25 team when Dyson, Kornienko and Skvortsov return to terra firma aboard the Soyuz TMA-18 which lifted them skywards on 4 April. ®